Advice Wanted Tool for front of 72mm filter thread lens

[ektar]

Greets; hopefully this generates some advice. I have an older telephoto lens with 72mm front filter thread. I need to remove the trim ring to access the front element. I can buy a set of the rubber tools to do that, but I can't find just a 72. Any suggestions as to what sort of cylindrical object I can try to grip that ring? Thx!

 

[lucien]

I think you could look into something like these, must be available in the USA
Amazon and the like

General PDP Template

www.canadiantire.ca

General PDP Template

www.canadiantire.ca

 

[lucien]

Mr. Flibble and Brian are our local camera experts lens and all. It would help if the make/model of lens was mentioned, so other's can look it up and take it from there.

 

[AlwaysOnAuto]

Is the trim ring recessed below the surface of the outer most edge of the lens?

 

[Brownie]

Photo would help. I've removed rings with everything from a jar lid remover to spanner wrenches. I've even found them loose enough to spin by jamming your thumb and finger on opposite sides and turning.

Find a solid rubber ball like a dog toy that's large enough and cut it in half or so.

 

[ektar]

Sorry, yes, it's recessed.
RMC Tokina 400/5.6
Yeah, it's dusty... haven't started cleaning it yet.

 

[Brian]

I use a lens spanner- similar to this.

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Mine will handle a 72mm slotted ring.

If I had to make something: I would probably cut a strip of foam rubber with a sticky side and attach to a ring to grasp the name ring. I've done that before, and worked. An old rubber mouse pad also works.

 

[Brownie]

No spanner slots or pinholes.

Thumbs and fingers gripping the ring and barrel, turn
Two-sided carpet tape on a rubber ball
If that fails, unthread the front barrel assembly from the main barrel and get to the glass that way.

 

[ektar]

Yeah, I wanted to unscrew the front assembly, but I loosened removed the two grub screws and it only unscrews about a turn and a half. It feels like the "stop" is internal. There are no other visible screws. The challenge is finding something that's roughly the right diameter. 72mm is an off size compared to most jars or glasses.

 

[Brownie]

Yeah, I wanted to unscrew the front assembly, but I loosened removed the two grub screws and it only unscrews about a turn and a half. It feels like the "stop" is internal. There are no other visible screws. The challenge is finding something that's roughly the right diameter. 72mm is an off size compared to most jars or glasses.

Are there only two?

 

[ektar]

Yeah, only two.

I found a plastic jar lid that let me get the ring off, so that part of job done. I would still like to get the front barrel off, because the hood won't stay in the shooting position, so there's some sort of felt or something that's given up. Also, it would let me access the front side of the second group in from the back. That piece is really recessed, so it's blind trying to get the spanner down in there to catch the slots. I got the last (first rear?) group out and cleaned, but there is haze on the inner side of the next group, that I need to clean.

 

[Brownie]

Have you tried some deep google fu? I've been shocked at the obscure lenses I've found disassembly instructions for. Sometimes it takes some unique keyword thinking. Worth a shot.

 

[ektar]

Yeah, I've tried a bunch, and will keep on.

By way of update, I have a jar of that crevice-cleaning goo; it turns out that the lid is pliable plastic, and pretty much exactly 71mm diameter. That got the trim ring off; I was able to pull the front element, the spacer and the second element. So those are clean. Still working on the mount end. So the remaining quandary is getting the whole front half off to fix the hood.

 

[Brownie]

I obviously can't see it, but I don't think you're dealing with another assembly screw, it sounds like a stop screw for the focus ring. Maybe 3 of them. Have you tried removing the focus ring cover if there is one? Sometimes they hide them under it. If the rubber is too brittle you may lose it though.

 

[ektar]

Okay. Update-ish.

Struggled getting the mount reinstalled; tiny click ball bearing wouldn't cooperate. Fixed that. Now I can't seem to get the aperture controls reconnected such that they behave. IIRC on the original FD mount, the blades aren't "loose" until mounted on the camera, or you trick the lens into thinking that it is. I got it reassembled, but the lever worked the blades all the time but the controls are not "connected" to the aperture ring.

Working on that, then will confirm infinity focus.

 

[ektar]

As to the front complex; that's independent of focus other than infinity adjustment; this is an internally focusing lens. I found the four set screws for the focusing ring, but those are just going to connect the ring and the focusing tube/mechanism beneath. The rubber started to creep when I was tryng to unscrew the front complex. Still no love on the aperture mechanism.

The pics below are what I'm looking at: The slotted piece at the top of the first picture supposedly controls the aperture setting. That has very little play in it as it sits. The rectangular stub at the bottom of the pic is the end of the lever that actually opens/closes the blades. In the second picture, the tall piece with the brass nub appears to engage the slot. That arm is spring loaded and "free" when the mount is in the "mounted" state, locked when it is in the "unmounted" state. It appears that the squared/closed off lever at the bottom is involved with aperture action during shooting (with a film camera). That is free/spring loaded all the time, but, it should not be so when installed and in the "unmounted" state. When I had it put together earlier, it operated the blades all the time, but the aperture did not change with the aperture ring.

So, such is my current state of lost.

 

[Brownie]

I 'fixed' (ahem) a 135/1.8 K mount that had a similar problem. The aperture blades were stuck due to old grease working back over the years. When I disassembled it the second half of the aperture lever was gone, as were some of the ball bearings. Once I got it apart I found the rest of the arm laying inside, pretty sure someone tried to fix it earlier and couldn't sort out the blades. I flushed them with cigarette lighter fluid and they freed up. Once I sorted out how to put the lever back together everything worked. However, I lost the little ball bearing for the detents on the aperture ring when reinstalling. I suspect it's still in the carpet, way down deep. Dust mites are probably using it for dodgeball. Either that or the vacuum took care of any hope I had of finding it. So, the lens works but the aperture won't stay where you put it.

When I hit a roadblock I yours, I research, research, research to make sure I've reached the end of the line, then at some point I shrug and start taking shit apart. I mean, if it doesn't work now, what have you got to lose? Take copious photos and notes and sally forth!

You might try the folks over at Photrio.com, lot's good repairmen there.

 

[ektar]

Cue Charlie Brown/Snoopy dancing music!!!

I got some advice over at MFLenses, and had correctly identified the function of the two levers. The slotted one controls aperture size, and the bottom non-slotted opens and closes the diaphragm, in an all or nothing fashion. That one worked. The aperture one turned out to have gotten jammed. Apparently when the opening lever popped loose when I took off the mount, it flicked something internal out of place. I used a fine crocheting needle to reach down and see what moved what, saw the out of place bit, and was able to bump it back into place. At that point the mount went back on easy-peasy. Everything appears to work properly. Focusing is smooth, aperture is dry. The hood is still loose when deployed, but a rubber band or big-a** O-ring will take care of that.

She's going to be a little homely; there's some dust of course, and some off-axis haze, but I look forward to seeing what kind of IQ she'll produce. Then I decide whether to keep 'er as a bargain "big gun," or let someone else enjoy it.

It was a tester, but everything I take apart teaches me something.

 

[Brownie]

Congrats!